# Calculation of electric current power - formula and online

Sometimes you can hear such a simple question: "what power is in the socket?". The answer, strangely enough, more often than this: 10 amperes. Or - 220 volts. It is clear that the question is stupid. But the explanation is not better - "And it's written on the socket".

•  Power and current
• Current strength and applied load
• Kettle and electric power
• Necessity of power calculations
•  Calculation of the electric current by the formulas
• Repair and construction of houses and apartments, features of calculations
• A photo

## Power and current

If we correctly answer the question posed, then for readers who are skipping physics lessons in childhood, we can say that the power of electricity depends on two quantities:

• voltage values;
• of the current.

In general, these two values ​​determine the power of both AC and DC. Memory may suggest something like: for a circuit segment, for a complete circuit. This echoes of the same school textbook of physics, which refers to the law of Ohm.

Yes, this famous law allows you to calculate the power of an electric current. Of course, the school program represented this law for DC circuits, but the essence of this does not change. The formula is eternal and unchanged: P = U x I.

To paraphrase Ohm's law into a simple language, we get a simple answer to the question about the power in the socket: the current strength depends on the load.

## Current strength and applied load

The trivial concept of this thesis will not allow us to carry out the elementary actions constantly committed by us, or by the people around us:

• Include one electrical extension cable in the other, plugging in both all available plugs from different, sometimes quite powerful, consumers of electricity;
• connect the other car to the ground battery of the car, connecting them with wires from the old electrical wiring;
• to build wires from an electric kettle with a twisted pair cable;
• install in the garage heater, 5 kW, connecting it to an ordinary outlet.

Similar examples of illiterate actions can be brought to infinity. Human carelessness knows no bounds. To avoid such mistakes anymore, let's analyze how to calculate the electrical power correctly.

## Kettle and electric power

Without hammering the head with the simplest formulas (there are deeds and more important than this), let us remember a simple ratio sufficient for its application in everyday life. Its accuracy does not correspond to the calculation formula, but it allows to remember that: 1 kilowatt of electricity is approximately 5 amperes of current in the 220-volt network.

Thus, it becomes clear that an electric kettle included in the kitchen socket consumes about 5 amperes of current. A incandescent lamp, with a power of 100 watts - is ten times smaller: 0.5 ampere. Of course, such primitive knowledge is needed for housewives, the calculation of the power of electric current is made by formulas.

## Necessity of power calculations

A person has little experience with the need to perform calculations (powers of a constant electric current) in everyday life. Most often, such a need arises when repairing a car, where the current source is the battery. Or some advanced user starts to choose a new cooler for his processor in the computer.

More often there is a need to conduct elementary calculations during repair work in the apartment, when selecting a burned power unit, etc.

## Calculation of the electric current by the formulas

There is a formula for calculating the electric current for a single-phase and three-phase network. Hardly anyone wants and can use them - to understand what is cosφ when replacing the electric wiring in the house or apartment is inexpedient.

You can actually make all the necessary calculations online. The Internet is packed with different tables, corresponding to charts and calculators. For very needy readers, you can add that the cable section for the lighting network is 1.5 square meters. mm. And for power supply sockets using a cable cross-section of 2.5 square meters. mm.

The rest of the calculations required for the production of electrical work in various fields of activity are best entrusted to specialists who use different instruments in their work: ammeters, voltmeters, phase indicators, insulation resistance meters, earth resistance meters, etc.

## Repair and construction of houses and apartments, features of calculations

To make the calculation of the electrical wiring in the apartment it is not enough to make the selection of the section of electric wires. In the electrical panel are installed and electrical machines, and protective devices and electric meter. These installation products are also selected and calculated in the design of the power supply project, which also calculates the number and parameters of protective earthing devices.

For calculation and selection of the types of wiring used in the manufacture of extension cords, the organization of temporary power circuits, it is necessary to understand that power cables for single-phase and three-phase circuits are different in number of cores, laying conditions, current loads and other parameters.

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When using cables and wires, it is necessary to take into account the material for the manufacture of conductors.

Presence in a country house, giving three-phase electricity consumers, such as a downhole pump, electric motors, welding equipment, requires taking into account their starting currents when selecting electrical cables. And when choosing an electric electricity meter - the active and reactive component in the power consumption, if the three-phase equipment is supposed to work continuously.

Good luck!

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